Bladder cancer is a cancer arising from cells in the urinary bladder. Most bladder cancers are transitional cell carcinomas, arising from epithelial cells in the inner lining of the bladder (urothelium). Other types of bladder cancers include squamous cell carcinomas, adenocarcinomas, sarcomas and small cell carcinomas.
Diagnosis of bladder cancer is commonly performed by cystoscopy, in which the bladder is examined visually using an endoscope (cystoscope). A biopsy is usually taken from areas of suspicious abnormalities to check for the presence of any cancerous cells.
Another method employed in the diagnosis of bladder cancer is urine cytology, in which a urine sample is analyzed under a microscope to detect the presence of cancer cells. Various imaging methods, such as X-ray and Computed Tomography (CT) have also been utilized for diagnosing bladder cancer, some of which involve injecting a dye intravenously to enable the visualization of the examined tissue.
In recent years, additional diagnostic means for bladder cancer have become available, such as urinary antigen tests and an assay for detecting chromosomal abnormalities in urine samples (UroVysion™).
The currently available methods have a number of drawbacks, as some of them are invasive, laborious and time consuming, and some are insufficiently sensitive and specific. In addition, diagnosis by pathological examination is carried out manually and is therefore subjective. Subjective results are problematic because there can be differences between results of the same sample analyzed by different pathologists, and even by the same pathologist in different times.
WO 2011/001274 and WO 2011/070441, assigned to the Applicant of the present invention, disclose methods for identifying DNA from a natural source and methods for categorization of DNA samples into different types of tissue, respectively, based on ratios of methylation levels at specific genomic loci.
There is an unmet need for improved methods and kits for diagnosing bladder cancer in subjects in need thereof, with high specificity and high sensitivity which do not require well-trained pathologists. There is further a need for objective, user-independent diagnostic methods.